Evolving trends in bio/chemical sensor fabrication incorporating bimetallic nanoparticles

Biosensor designing took a giant leap in its path of evolution after its merger with a wing of nanotechnology. Dramatic properties like high surface area to volume ratio, enhanced chemical and optical properties of nanoscale materials have revolutionized sensor technology in terms of their analytical performance. Many metallic nanoparticles (MeNPs) like gold, silver, platinum, palladium nanoparticles, etc. have been tremendously exploited for improving sensor performance. Over the years, there has been slow but steady shift in nanoscience research with an aim to explore composite MeNPs like bimetallic, trimetallic nanoparticles, etc. So far, these engineered nanoparticles are shown to possess multifunctional properties which are providing several advantages over monometallic nanoparticles (mono-NPs). As a result of these properties, composite MeNPs, particularly bimetallic nanoparticles (BNPs), have sought the attention of sensor engineers and since then there has been rapid rise in the number of reports of sensors incorporating BNPs within a brief period of time. Keeping this pivotal fact in consideration, we have complied this review to give readers a clear insight in the possible ways BNPs can be synthesized that would render them to possess crucial characteristics desired for bio/chemical sensor fabrication and their applications. We have also discussed different characterization techniques that have been applied to investigate various properties of the BNPs along with a table that gives information on how each technique is different and in what ways they complement each other. Moreover, a comprehensive report on the incorporation of different BNPs in sensor fabrication for detection of hydrogen peroxide (H2O2), glucose, pesticides, nucleic acids, proteins, cancerous and bacterial cells has been described. The comparison of analytical performance of the biosensor design incorporating mono-NPs and BNPs, in terms of linear range (LR), limit of detection (LOD), sensitivity, and specificity, has also been discussed to show the importance of BNPs in sensing matrix.